NPE for annotation reference to constant in binary file

it occurs because 1.7 isn't quite capturing class file constants correctly. For this code

class C {
  public final static String value = "abc";
}

groovy 1.7 produces this decompiled output:

public static final java.lang.String a;

whilst groovy 1.8 produces this decompiled output:

public static final java.lang.String a;
  Constant value: String hello

without the classfile capturing the 'constant-ness' we cannot (easily) work out what the value is from a purely static reference. The code in JDTClassNode.fieldBindingToFieldNode cannot cope with this situation. In my testcase I can only get the error on an incremental build (because at that point the class containing the constant only has a binary representation). I can imagine other situations where a reference is made into a jar containing the constant and that would cause all full builds to fail.

I'll spend a few mins thinking about solutions but we may have to just say this kind of thing isn't supported for 1.7.

I think we 'get away with it' for pure groovy compilation (where the reference to the constant is into something in a jar) because groovyc resolves references by loading classes and driving static initializers (yuck).

I can guard to catch the problem where the constant is not correctly represented, this at least causes a real message to come out rather than the NPE. The kind of messages that will come out in the situation are now:

/Project/src/A.groovy: 1 Groovy:expected 'Const.instance' to be an inline constant of type java.lang.String not a property expression in @Anno
/Project/src/A.groovy: -1 Groovy:Attribute 'value' should have type 'java.lang.String'; but found type 'java.lang.Object' in @Anno

committed a test and the guard. This all works fine on 1.8 so not currently going to do the heavy lifting to fix it for 1.7

Fixed.